Acoustic device



' Nov. 27, 1928.

' 1,693,297 J.- HUTT ET AL ACOUSTIC DEVICE Filed May 11, 1926 2 Sheets-Sheet 1 Inventor's: Joseph Hat's, George H. Bird, by Their Attorneg.

Nov. 27, 1928. 1,693,297 J. HUTT AL ACOUSTIC DEVICE Filed May 11, 1926 k 2 Sheets-Sheet 2 v I V17 Inventors: Joseph Hutb, George H. Bird,

b W I Their Attorney.

Patented Nov. 27, 1928.

UNITED STATES PATENT OFFICE.

JOSEPH HUTT AND GEORGE H.;BIRD, 0F COVENTRY,- ENGLAND, ASSIGNORS-TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ACOUSTIC DEVICE.

.Apiilicationifiled May 11, 1926, Serial No. 108,355. and in Great Britain June 8, 1925.

The invention relates to telephone receivers and transmitters, loud speaking telephones, microphones and the like apparatus in which avibratory diaphragm is excited magnetically in order to generate sound waves or is excited. by sound waves so as to generate corresponding fluctuating electric currents. v In telephone receivers the vibratory magnetic diaphragm is usually clamped in position on the edge of the casing'by means of a screw thr "1 cap which engages with a corresponding screw threaded portion on the casing. The screw threads on the casing and cap involve either separate thread cutting operations or the molding of the screw threads in corresponding molds. By avoidin g the screws,"the molds become less expensive and the operation of extracting the molded product is simplified.

The object of the present invention is to provide meansfor clampin the diaphragm in position independently o the cap or other part so that the casing, cap .or other cooperating part need not be provided with screwthreads. I v

According to the invention, a diaphragm is employed which may be of the same or less diameter than the external diameter of the casing, and its edge is held in a clam ing ring adapted to hold it over the mouth 0 the casing. The clamping ring may consist of sheet metal pressed in a jig, so as to gripthe marginal portion of .the diaphra m and provide a depending rim adapte to be pressed over 'the edge of the casing. In another manner. of construction a short cylinder of sheet metal internally of the same diameteras the diaphragm is provided at the top end with V-sha ed notches and with cuts in the bottom end so that when the ton ues at the top end are ressed flat on the diap ragm they come close y adjacent one another and then alternate parallel sided tongues at the bottom end are pressed flat on to the underside of the diaphragm whilst the remainder are used to grip the side of the casing and may be presse under a flange or into a groove. In a modification of this construction incisions are'made inthe cylinder to form tongues to bepressed flat on the underside. of the marginal portion of the diaphrag'm whilst the lower edge of the cylinder is left intact to give additional strength.

With these arrangements the diaphragm is held over the open-end of the casing without the necessity of. the cooperation o the cap or other constructional part of the device, and thecap or other part need only make a sliding fit over the edge of the casing or of the clamping membe p The novel features which we believe to be characteristic of our invention are set forth with particularity in the appended claims.

Our invention itself, however, will best be understood from reference to the following of.an instrument casing 12 and it is clamped" In this pos1t1on by means of an annular flanged ring 13, the flat disk portion of which rests upon the outside ofthe dia phragrn, while the lower depending rim is a close fit against the outside of the casing 12. A cover 14' of, the instrument, preferably of metal and the depending flange 15 thereof makes a tight fit against the cooperating part of the clamping member 13.

In the modification shown in Fig. .2 the clamping member 13 is provided with an.

outwardly extending flange 16 against which the end of thefiange 15 of the cover 14 rests. The middle portion of theclamping member 13 is raised, as at 17 and terminates in an annular upstanding flange 18 arranged to lie against the cooperating flange 19 on the cover 14.

In the modification shown in Fig. 3 the .end of theflange 16 is curled around the end of flange 15, as indicated at 21, and also the end of the flange 19 is curled around the inner portion of the clamping member 13, as indicated at 22.

Referring now to Fig. .4, the clamping member 13 is provided with a number of axial slits in its depending rim portion and the material between each pair of slits isv alternately bent upwardly, indicated at 23,

against the under side of the diaphragm 11, leaving a number of tongues 24 to engiz e against the outside of the casing 12. l ie disk portion of member 13'may be made by providing V-shaped slits and then bending over the material between each slit, as shown at 25.

In the arrangement shown in Fig. 5, the clamping member 13 is arran ed to engage the cover 14 externally thereof as indicated at 26, and a downwardly projectin rim 27 is provided on the cover to engage t e upper side of the diaphragm. a

Fig. 6 shows a modification which differs from Fig, 5 mainly in that the clamping member 13 is shaped to provide a more artistic appearance. a

What we claim as new and desire to secure by Letters: Patent of the United States; is, v

1. In an acoustic device, a perforated cover having a depending flange, and a flanged ring supported within said cover by frictional engagement with the depending flange. v

2. In combination, an acoustic device comprising a flanged cover provided with a central opening extending therethrough, a diaphragm mounted within the cover, and a flanged ring, arranged to support said diacom rising a flanged ring pressed against the outer surface of said casing, and a flanged cover co-operating with said diaphragm and adapted to slidingly engage said flanged ring, said cover having a central I opening extending therethrough.

5. An acoustic device comprising a casing, a diaphragm associated with one dnd of the casing, frictional means comprising a flanged ring for maintaining the diaphragm in position, and a perforated cover mounted above said diaphragm and adapted to friction'ally engage said ring. p

In witness whereof, we have hereunto set our hands thisv19th day of April, 1926.

JOSEPH HUTT. GEORGE H. BIRD. 

